JB Weld on ABS drainpipe

pjb999June 5, 2008

SO apparently JB is pretty good for this- previous homeowners had drilled 3 holes into a drainpipe putting up a shelf and never knew it, I noticed a little dampness on the floor and around the cleanout at the base of the pipe. I consider myself so, so lucky as this pipe serviced a toilet as well as a shower/bath/sink yet nothing overly stinky came out, I did end up removing a 7' section of drywall around it ( the end of an alcove, basically) because the capilliary effect propelled water along the wall between the plastic moisture barrier and the drywall. One section near was soft the rest of the drywall was more or less fine and might have been ok if it was allowed to dry, but I didn't want the possibility of mould so I removed more than I had to.

The area does not allow a lot of room to work and I decided cutting the whole section out and replacing it (the pipe) might be worse by the time I cut it all out and turned the pipe joiners into slip rings (no room for the pipe to move) I might be better off patching those 3 little holes not to mention the potential mess cutting out a sewer pipe....

So in the end I patched the holes with JB weld, made sure the holes were dry (just used plain JB couldn't find the water stuff) and filled allowing a key in the hole, then a second layer using used dryer sheet like fibreglass cloth, then a final layer over it,

It has sat for several weeks (got waylaid after I pulled the wall out) and the repairs seem perfect - not a sign of a leak. I also ran JB arould a pipe joint as double insurance after a tight fit with the abs cement etc, and all that looks good too.

Just in case anyone's wondering - JB seems to do ok for this.

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Using ABS cement to attach even half of a slip fitting over the area would have been a better repair.

    Bookmark   June 6, 2008 at 8:03PM
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I had thought of an abs patch using a cut section of pipe but inner to outer rarely lines up without a gap, but a slip fitting (I didn't know they made them, I was going to make my own by removing the stop in the middle) would make sense as it'd line up well.

Why do you say it'd be better? I made sure it was clean and dry, and the hole was plugged, allowing for some key, and I did several layers over. So far looks ok it's been several weeks and I hadn't gotten around to redoing the drywall so it's been well...tested. ABS is specifically named as ok for JB weld.

    Bookmark   June 7, 2008 at 2:33AM
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It never ceases to amaze me as to how many uses some people seem to find for JB weld. Personally, I have never purchased a container of JB Weld so perhaps I am missing out on one of lifes miracles however, Over the years I have been called upon to repair problems that were at one time or another repaired with JB Weld or any number of other Epoxies, glues or tape of one sort or another. I find it most interesting to see where people have used one of those products to repair a sink tailpiece or P-trap, especially when one considers that you can purchase a new tailpiece or P-trap for about half the cost of a package of JB Weld.

In regard to the use of JB Weld on a PVC or ABS DWV (drain, waste &Vent) pipe it must be remembered that both PVC and ABS have a very high co-efficient of thermal expansion and even though the JB Weld repair may seem ok at the time of repair or for a short period thereafter, the question is, can you stake your professional reputation on the fact that it will hold up for the life of the pipe, and not eventually break its adhesive bond from physical changes in pipe wall dimension? Keep in mind that even though the pipe is within the climate controlled portion of the structure nonetheless there are constantly air currents in the pipe which could draw in triple digit air in mid summer or sub-zero air in mid winter which would radically effect the pipe dimension.

The prescribed method of repairing the pipe is to cut out the damaged section and replace it however if the damage is simply a minor hole or two inadvertently drilled into the pipe wall in a very close proximity it would seem silly to cut a major chunk of pipe out. In this case, if the three holes in question were only effecting a 3 or 4 linear inch section of the pipe which could be easily covered with a coupling the proper method would be to cut the pipe at a point where the coupling could cover all the damage, then shift one section of the pipe to the side and slip a "Repair Coupling" or a Fernco coupling on one section of the pipe, realign the pipes then apply primer and glue and slid the repair coupling into place or simply slide the Fernco into place and tighten the band clamps.

NOTE: A common PVC or ABS coupling has a raised depth stop midway through the coupling to insure that both pipes are installed to the proper depth during installation. A "Repair Coupling" has no internal stop so it can easily be slid on one pipe, then when the pipes are realigned it can be slid back to the final position.

Although definitely not code approved, in a worst case scenario I might be tempted to cut a repair coupling in half and glue it in place as was mentioned above, however I would also place a stainless steel band clamp around it.

It was also mentioned above that they didnÂt think the problem was too serious because there was no "Stinky odor" coming from the pipe. Do not be lulled into believing there is no sewer gas leak because you canÂt smell it. Of the four principal gases that make up sewer gas, nitrogen, carbon dioxide, methane and hydrogen-sulfide, the first three are odorless asphyxiates. The fourth gas, hydrogen sulfide has a very strong rotten egg odor however in elevated concentrations it also has the capacity to quickly anesthetize the olfactory nerve thereby making further detection by smell impossible. In addition, both hydrogen sulfide and methane are flammable and in higher concentrations methane is explosive. (Methane is the base component of natural gas, in fact, in Michigan there is a commercial dairy operation that has installed digesters to convert the manure from their dairy herd into methane fuel to power engine driven generators to power the whole farm & dairy operation, and Windex has now tapped the methane gases from a nearby landfill to power one of their factories).

As if these facts are not problematic enough, it must also be mentioned that some of these gases are lighter than air while others are heavier than air, therefore it is quite common for sewer gas to build up in a structure, but because of the specific gravity of the gases they tend to stratify near the floor or the ceiling and can go undetected for a long period of time.

The bottom line, do not take any chances with leaks or dry traps in a DWV system.

    Bookmark   June 7, 2008 at 2:31PM
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I presume the fernco coupling is one of those rubber things you slip over cast iron etc, I hadn't thought of those but I wouldn't have thought they'd be suitable to be drywalled over, it's not a six inch wall so the pipe really fills the spot between both sides. Like I said I wanted to cut the section out but was concerned I might make a much larger problem, because I wasn't confident there was enough room to move/swing the pipe to put a slip fitting on. I take your point regarding them but if I was just slipping something over I'd still want to plug the hole with something.

Until I removed the drywall the holes were partially plugged with screws from the bracket the previous homeowner morons screwed through the pipe, I hadn't thought of the methane aspect of it - I'm familiar with is as some places in Australia have tapped former dumps for the methane, and run converted diesel generators on it.

My remark about the odour was more pertaining to the liquids that have leaked from it more than the gases, I was considering I'd gotten off lightly because, really we're talking sewage, and it wasn't anything like it, most of the time I think the only time the water hit the screws and leaked out was probably when the shower was running. I knew it was serious (I do kick myself for not fixing it sooner, I'd known for a couple of months but I didn't know it was wicking along the wall, to be on the safe side I removed all the drywall and will probably replace all the insulation to avoid mould issues.)

I pondered how to fix it for a couple of days before I decided to use the JB, I know you have something against it in these circumstances which is fair enough - ordinarily I'm pretty paranoid/overcautious and would certainly have gone the replacement section route (and may still look at doing it if I'm certain I can guarantee I'm not going to make it worse - like I said the gap is so small I'm not even sure if a slip ring would fit without furring out the wall (again, a possible option)

Part of the reason I went with it is I've used JB Weld quite a few times over the past few years and it does seem to bond well with plastics, better than any other cement I've seen. I repaired a styrene freezer door (one of those small one door fridges where the freezer is just a plastic door over the coils etc) - well more like fabricated parts. The hinges broke away because someone hadn't defrosted it and then forced the door open, so I had to build the parts up with JB then machine them back down with a Dremel. As I say I think it was styrene but the cold/coefficient thing seemed ok, the door was still perfect when I sold the fridge over a year later.

    Bookmark   June 8, 2008 at 2:44AM
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The correct cements for ABS and PVC have a bunch of solvent and the base pipe material dissolved in the solvent.
They actually 'melt' the surface of the pipe to produce a very uniform joint.

The joint is now the exact same material as the pipe.

    Bookmark   June 8, 2008 at 1:20PM
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Brickeye is absolutely correct, while we commonly call it gluing, technically the process for joining ABS & PVC pipe is "Chemical Welding" and it has little to nothing to do with whether or not a glue will bond to the plastic.

The glue literally melts the plastic and fuses the pipe and fitting into one solid mass.

Where prescribed it is also vital to use the primer because the primer serves two functions.

  1. It dissolves the surface glaze off the pipe and fitting wall to allow the glue to react directly with the pipe or fitting core material

2. It serves as a catalyst for the glue.

    Bookmark   June 10, 2008 at 8:35AM
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Thanks, I do understand the principle of solvent welding vs gluing and I may yet replace that section, but I think the repair I've done will work, obviously if I can replace the section, it'd be preferable.

    Bookmark   June 11, 2008 at 7:15PM
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In a curious twist of fate, I came across this idea of drainwater heat recovery, this pipe is a drain, I was considering removing the repaired section anyway, it seems like fate! I will have to fur out the wall and/or take a couple of other steps, but it seems like a cool idea to me.

    Bookmark   June 17, 2008 at 9:54PM
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